The ornamental design for a solarpanel, as shown and described.
FIG. 1 is a front elevational view of a solar panel showing my new design;
FIG. 2 is a rear view thereof; and,
FIG. 3 is an enlarged view of portion 3 in FIG. 1.
The dash-dash broken lines shown represent the portions of the solar panel that form no part of the claimed design. The dash-dot broken lines define the bounds of the claimed design and form no part thereof. There is no substantial thickness of the claimed design and all the elements of the claimed design are flat and coplanar.